People who repeatedly commit alcohol-related crime will be forced to wear ankle tags that monitor if they are still drinking, under a year-long pilot scheme.

The "sobriety tags", which will be worn around the clock, will enforce abstinence by measuring a person's perspiration every 30 minutes and testing to see if it contains alcohol.

If any trace is found, an alert will be sent to the offender's probation officer and they can then be recalled to court, where they could face sanctions such as a fine or be re-sentenced.

The tags register alcohol consumption but do not monitor movement or where people are.

The 12-month scheme is being trialled in four London boroughs - Croydon, Lambeth, Southwark and Sutton.

It is anticipated that up to 150 offenders will be fitted with the tags. They will be banned from drinking alcohol for up to 120 days, and the tag will test them to see if they flout the ban.

Offenders will be screened before being tagged, and the scheme will not be used on people who are alcohol-dependent and require specialist support.

The scheme, being introduced by London Mayor Boris Johnson, builds on a similar scheme in the US and aims to reduce alcohol-related reoffending, ease pressure on the police and courts, and make streets safer.

Alcohol-related crime is estimated to cost the UK between £8 billion and £13 billion every year, while 40% of all accident and emergency attendances are related to alcohol misuse.